Motor control



June 14,1927; 1,632,603 B. W. JONES MOTOR CONTROL Filed. Dec. 5. 1926 v Invehtcw: BenJaminW Jones,

Hi s Attorney.

Patented June 14,1927. 1,632,603-

UNITED [STATES PATENT" orrrcn.

nnnrmrn w. corms, or scnnnncmnx, new xonx, ASSIGNOR 'ro ennnm mermc conrm, a conrona'rron or new YORK.

moron common.

Application filed DeoemberS, 1926. Serial no. 152,490.

My invention relates to improvements in torque, and the value of the. motor armature systems of control for electric motors wherecurrent reduces to a predetermined value, by the motor speed is automatically reguthe switch w ll automatically open so as lated to meet predetermined conditions. Alt effect the reinsert on of the resistor in the though the invention is not necessarily hmfield winding circuit and permit a higher to ited thereto, it has a particular application S ced of operation. In case the current in to motor drives wherein the load driven by t e motor armature circuit is above a prethe motor is apt to overhaul the motor and e mined value, such as during the accelthe load is apt to obtain a dangerous undecrating period lowerlng direction of motor sirably hi h speed. Such conditions are operation, (drlvmg torque being exerted by .encountere in motor driven hoists, and in t h SWltCh Will m gn cally hold particular hoist drives provided with a sen cts olqsed so as to insure a relatively ries wound motor, the series field of which, hlgh field excitation for the motor. After during lowering operations, is connected in. the motor is up to stable speed correspond- 15 a different circuit from the circuit in which mg to strong motor field excitation, 1f the the armature is included, as for example, the load should overhaul the motor and the difield is connected in shunt relationwith the l n of the motor armature current be armature during lowering operations. For r v rsed, the switch will automaticall resuch drives it is desirable to regulate the close its contacts and hold the same 0 osed 20 lowering speed of the motor and at the same magnetically at all value of th meter time permit as high a speed of lowering as mature current in this direction. The motor is practical when conditions are such that thus utomatloally protected against a a high lowering speed is permissible. The hlgh operating-speed durin the lowering of principal object of my invention is the proh load, and in case the oad is relatively 25 vision of an improved control for the mohght, a comparatively high lowering speed tor whereby this result is secured. 1S automatlcally q In carrying my invention into efiect in the e mpanylng drawing I have inform which I now re ard as the preferred (heated 111 a y p dlagmm motor form thereof, Iprovi e a, cgntrol for COIltl'Ol system Wh1Cl1 iIlCOIPOIiLlDBS the in- 30 the electric motor so arran ed as to auto- V h 1on. It will be understood by those matically govern a resistor m the fi ld ei skilled in the art that this diagram is in- 7 Quit f th motor h the motor fi ld i dtended to merely llustrate the connections a ing is connected to produce shunt characterf e mo or and its control for the operaistics for the motor, the resistor being contlon of the motor in such a direction in 35 trolled by an electromagnetic switch which W he autpmatlo protection aflorded by automatically takes into account the value the Invention 1S q In other words, and direction of the current in the motor ar- 9 mp1ate that my mventlon will be used mature i it in a reyersmg control system in which the I th f d f f my in ti I motor is operated in one direction to pro- 40 provide a series electromagnetic switch or duce a torque tending to operate a load in contactor for controlling the resistor in the a corresponding direction and to operate in shunt field circuit, and this contactor is prefthe opposite direction -to set up a torque for erabl of the type disclosed and broadly and either operating or regulating the movement speci call claimed in the Patent No. 1,445,- of the load in an opposite direction. I have 45 994, date February 20, 1923, to Eugene R. not shown such reversing control since it is Carichoif and myse f. In the system of the of itself old and well known and particupresent invention the contacts of this switch larly since the essence of my invention reare biased so as to be normally in their sides in the simple control indicated in the closed position and normally shunt the re accompanying drawing. v 5 sistor in the field circuit of the motor while Referring to the diagram the electric conditions are such that a high field excitamotor is provided with an armature A and tion is desirable. In case the current in the a series type field winding F, which is motor armature circuit is in a certain direcshown connected in a diiferent circuit than tion, as for example, motor lowering vdirecthe motor armature, in that the winding is 55 tion, with the motor exerting a driving connected in shunt relation with the motor armature. The motor is connected to the source of supply 10 throu h the operation of the line contactor 11, w ich is governed by the master switch 12. As before stated, the dia ram indicates the control of the motor or only one direction of operation, and I would haveit understood that the invention is applicable to reversing systems of control, but such s stem has not been shown since it would a d nothing to an understandin of the invention.

It wi 1 also be understood that during operation of the motor in one direction, as for example, the hoisting direction, the field windmg F will be included in series relation with the motor armature instead of in shunt relation therewith, as shown in the drawing. The energization of the field windingRF is overned by means of the resistors 1 an R and the current in the motor armature circuit is regulated by means ofthe resistor R The resistor R in the field winding circuit is governed by the series contactor 13, which is of the construction and arrangement disclosed in the said Carichofi and ones Patent No. 1,445,994, dated February 20, 1923. This contactor is provided with a set of main contacts 14, one of which is operated by means of the movable magnetic member 15, the contacts being normally biased to their closed position, as indicated in the drawing. This contactor is also 'rovided with a series winding 16 and a unt winding 17, corresponding to the respective series and shunt windings of the contactor of said patent, and these windings are dis sed on a magnetic circuit as s cified in t e patent. The ener ization of this shunt winding 17 is contro ed by the auxiliary switch 18 associated with the line contactor 11.

It is assumed that the motor is connected to drive a load, which under some conditions, may be of such a nature as to overhaul the motor. With such assum tion the operation of my invention is as to lows: In order to connect the motor to the source of suppl 10, the master switch 12 is. first closed, thereby energizing the line contactor 11 to close its main and auxiliary contacts. The closing of the main contacts of this switch wil energize the motor from the source of sup ly and the resistor R will be maintained s unted by means of the contactor 13. The shunt winding 17 of the contactor 13- will be energized through the auxiliary switch 18 of the line contactor 11.

While the current taken by the motor is in excess ofa certain value, as happens during the acceleration interval, the contacts 14 of the series contactor 13 will be magnetically,held closed so that a relativel high ener ization for the field windin is secur In case the load being owered is .comparatively light (as .is the case in a hoist when an empty hook is being lowered), and the current in the motor armature circuit reduces to less than a predetermined value after the acceleration interval is past, the winding 16 of contactor 13 will effect operation of the movable magnetic member 15 to open the switch. contacts 14 and thereby insert the resistor R in the circuit of the field winding F. This will reduce the energization of the field winding and efiect an increased speed of operation of the motor and the associated load. If while the resistor R is inserted in the circuit of the field winding F, the speed of the load should increase to such a value that'the motor is overhauled by the load, the current in'the motor armature circuit will reverse and this will reverse the direction of current through the series winding 1? of the contactor 13. The contactor 13 has the peculiar characteristic, as is set forth clearly in the aforementioned' patent, that the movable magnetic member 15 will be 0 erated to and magnetically held in a biase position for all-values of reversed current through the 'winding 16. This is brought about b the cooperation with the shunt winding 1 as explained in the said patent.

This contactor, therefore, operates to antomatically include the resistor R in the field winding circuit of the motor in case the load being operated b the motor is less than a predetermined va ue and the armature current of the motor is less than a predetermined value and such armature current is in a predetermined direction. If, however, the current in the motor armature circuit reverses as is the case when the load overhauls the motor and the motor becomes a nerator, the resistor R, will be magnetically shunted by the contactor 13 and the shunting will be maintained for all values of such reversed current. The lowering speed is thusautomatically limited and at the same time a high lowering speed is permitted in case conditions are proper for such hi h speed of operation.

In accor ance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that t e invention can be carried" out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a motor having its armature included in one circuit and a field winding included in another circuit, a resistor for governing the energization of said winding to govern the motor speed, a switch based to the closed position for shunting said reslstor, and an electroresponsive deill 1,esa,eoe

vice energized responsively to the motor armature current and provided with means for automatically effecting the o ning of said switch and the insertion of said resistor in the circuit of said field winding when the motor armature current is in a predetermined direction and 1s less than a predetermined value, the said device being provided with windings for magnetically holding said switch in its biased position for all values of motor armature current above said predetermined value and for all values of motor armature current when said current is in the direction opposite to said predetermined direction.

' 2. In combination, a motor having its ar mature included in one circuit and a field winding included in another circuit, a re sistor in the circuit of said field winding, and a series .contactor biased to normally shunt the said resistor, the said contactor having a series winding included in the motor armature circuit and a magnetic structure energized thereby for magnetically holding the said switch'in its biased position for all values of the motor armature current above a predetermined value and in a predetermined direction and for magnetically opening the said switch to open the shunt about said resistor when the motor armature current is less than the said predetermined value and in the said predetermined direction, the said contactor being firovided with a shunt winding which insures the opening of the oontactor to include said resistor in the circuit of said field winding at all values of the motor armature current less than said redetermined value and in said predetermmed direction, and 2301' insuring that said contactor will magnetically maintain the shunt about said resistor for all values of the motor armature current when said current is in a direction oyfosite to the said predetermined direction. witness whereof, I have hereunto set my hand this 2nd day of December, 1926.

BENJAMIN W. JONES. 

